Effects of lithium on evoked potentials and performance during sustained attention.

Two versions of the continuous performance test (CPT) differing in complexity were administered to 15 patients with bipolar affective disorder, manic type before and after treatment with lithium. Reaction time, performance accuracy, and the late positive component (LPC) of the event related potential evoked by the task were measured concurrently. Lithium treatment decreased errors of commission on both CPT tasks, although the difference was significant only for the simpler task. Reaction time was significantly increased by lithium treatment on the more difficult CPT task, LPC amplitude to the target stimulus on the difficult CPT was significantly increased by lithium. The data are interpreted as consistent with an attention-enhancing effect of lithium, coupled with a general reduction in the tendency to respond to stimuli.